[libFuzzer] add threads to the fork mode: now you can pass -fork=N to run N concurrent workers. Fork mode is still work-in-progress.

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk/lib/fuzzer@353997 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/FuzzerDriver.cpp b/FuzzerDriver.cpp
index 00dae3f..434c481 100644
--- a/FuzzerDriver.cpp
+++ b/FuzzerDriver.cpp
@@ -725,7 +725,7 @@
   }
 
   if (Flags.fork)
-    FuzzWithFork(F->GetMD().GetRand(), Options, Args, *Inputs);
+    FuzzWithFork(F->GetMD().GetRand(), Options, Args, *Inputs, Flags.fork);
 
   if (Flags.merge)
     Merge(F, Options, Args, *Inputs, Flags.merge_control_file);